Field of the Invention
This invention relates generally to pumps, and more specifically to systems and methods for preventing diffusers in pumps such as electric submersible pumps from bursting or collapsing in over-pressure and/or under-pressure conditions.
Related Art
Oil and natural gas are often produced by drilling wells into oil reservoirs and then pumping the oil and gas out of the reservoirs through the wells. If there is insufficient pressure in the well to force these fluids out of the well, it may be necessary to use an artificial lift system in order to extract the fluids from the reservoirs. A typical artificial lift system employs an electric submersible pump which is positioned in a producing zone of the well to pump the fluids out of the well.
An electric submersible pump system includes a pump and a motor which drives the pump. The electric submersible pump system may also include seals, gauge packages and other components. The electric submersible pump system commonly utilizes a centrifugal pump that has multiple stages, each of which has an impeller and diffuser. The impeller spins, forcing fluids from the well radially outward and upward toward the diffuser. The diffuser converts the kinetic energy imparted by the impeller to pressure which drives the fluid upward. The diffuser typically also directs the fluid inward, toward the axis of the pump, where it can be passed to a subsequently positioned impeller.
Although electric submersible pump systems are designed to fit within the borehole of a well, and are typically less than ten inches wide, they may produce hundreds of horsepower. These systems may develop thousands of pounds per square inch of pressure, which may cause diffusers to burst. Conversely, when the systems have been operating and are stopped, underpressure conditions may develop within the diffusers, causing them to collapse.
It would therefore be desirable to provide systems and methods to prevent damage to diffusers that could result from overpressure and underpressure conditions.